Head to the hobby shop and look for the spring tube benders, or the auto supply stores for the hydraulic line benders, or Home Despot in the plumbing dept there are a number of different types, if nothing else you can get an idea of the working principals of the differing types.
All version do requires some practice at making graceful bends, curves or arcs. As with the hickey benders for electrical conduit. Practice, practice.
You can always try the old instrument makers stand by of water with some dish soap plug both ends and freeze the tube if it will fit in your freezer. This one or using table salt crystals paced in to a sealed tube all require some practice.
Or if there is nothing that will be flowing thru the inside, you can try some wax bees wax melted and poured in it. Or use some chasing/repousee pitch and then melt it out after wards.
The most important thing is to anneal the tubing before you star bending. Most short sections of tubing is extruded or drawn thru dies which work harden the material. And if you do multiple bends it will work re-harden it.
